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ISL3232E, ISL4221E, ISL4223E
Data Sheet February 13, 2008 FN6045.3
QFN Packaged, 15kV ESD Protected, +2.7V to +5.5V, 150nA, 250kbps, RS-232 Transmitters/Receivers
The Intersil ISL3232E and ISL4221E, ISL4223E devices are 2.7V to 5.5V powered RS-232 transmitters/receivers which meet ElA/TIA-232 and V.28/V.24 specifications, even at VCC = 3.0V. Additionally, they provide 15kV ESD protection (IEC61000-4-2 Air Gap and Human Body Model) on transmitter outputs and receiver inputs (RS-232 pins). Targeted applications are PDAs, Palmtops, and hand-held products where the low operational, and even lower standby, power consumption is critical. Efficient on-chip charge pumps, coupled with manual and automatic power-down functions, reduce the standby supply current to a 150nA trickle. Tiny 5mmx5mm Quad Flat No-Lead (QFN) packaging and the use of small, low value capacitors ensure board space savings as well. Data rates greater than 250kbps are guaranteed at worst case load conditions. The ISL4221E is a 1 driver, 1 receiver device and the ISL3232E and ISL4223E are 2 driver, 2 receiver devices that, coupled with the 5mmx5mm QFN package, provide the industry's smallest, lowest power serial port suitable for PDAs, and hand-held applications. The 5mmx5mm QFN requires 40% less board area than a 20 Ld TSSOP, and is nearly 20% thinner. The ISL4221E, ISL4223E versions feature an automatic power-down function that powers down the on-chip power supply and driver circuits. This occurs when an attached peripheral device is shut off or the RS-232 cable is removed, conserving system power automatically without changes to the hardware or operating system. It powers up again when a valid RS-232 voltage is applied to any receiver input. Table 1 summarizes the features of the IC's, while Application Note AN9863 summarizes the features of each device comprising the 3V RS-232 family.
Features
* Available in Near Chip Scale QFN (5mmx5mm) Package, which is 40% Smaller than a 20 Ld TSSOP * ESD Protection for RS-232 I/O Pins to 15kV (IEC61000) * Meets EIA/TIA-232 and V.28/V.24 Specifications at 3V * RS-232 Compatible with VCC = 2.7V * On-Chip Voltage Converters Require Only Four External 0.1F Capacitors * Manual and Automatic Power-down Features (Except ISL3232E) * Receiver Hysteresis For Improved Noise Immunity * Guaranteed Minimum Data Rate . . . . . . . . . . . . . 250kbps * Wide Power Supply Range . . . . . . Single +2.7V to +5.5V * Low Supply Current in Power-down State . . . . . . . .150nA * Pb-Free Available (RoHS Compliant)
Applications
* Any Space Constrained System Requiring RS-232 Ports - Battery Powered, and Portable Equipment - Hand-Held Products (GPS Receivers, Bar Code Scanners, etc.) - PDAs and Palmtops, Data Cables - Cellular/Mobile Phones, Digital Cameras
Related Literature
* Technical Brief TB363 "Guidelines for Handling and Processing Moisture Sensitive Surface Mount Devices * Technical Brief TB379 "Thermal Characterization of Packages for ICs" * Technical Brief TB389 "PCB Land Pattern Design and Surface Mount Guidelines for QFN Packages"
TABLE 1. SUMMARY OF FEATURES NO. OF NO. OF PART NUMBER Tx. Rx. ISL4221E ISL3232E ISL4223E 1 2 2 1 2 2 QFN PKG. AVAILABLE? YES YES YES DATA RATE (kbps) 250 250 250 Rx. ENABLE FUNCTION? YES NO YES MANUAL POWER-DOWN? YES NO YES AUTOMATIC POWER-DOWN FUNCTION? YES NO YES
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright (c) Intersil Americas Inc. 2004, 2007, 2008. All Rights Reserved All other trademarks mentioned are the property of their respective owners.
ISL3232E, ISL4221E, ISL4223E Ordering Information
PART NUMBER ISL3232EIRZ* (Note) ISL4221EIR* ISL4221EIRZ* (Note) ISL4223EIR* ISL4223EIRZ* (Note) PART MARKING ISL3232 EIRZ ISL 4221EIR ISL4221 EIRZ ISL 4223EIR ISL4223 EIRZ TEMP. RANGE (C) -40 to +85 -40 to +85 -40 to +85 -40 to +85 -40 to +85 16 Ld QFN 16 Ld QFN (Pb-free) 20 Ld QFN 20 Ld QFN (Pb-free) PACKAGE 16 Ld QFN (Pb-free) PKG. DWG. # L16.5x5B L16.5x5B L16.5x5B L20.5x5 L20.5x5
*Add "-T" suffix for tape and reel. Please refer to TB347 for details on reel specifications. NOTE: These Intersil Pb-free plastic packaged products employ special Pb-free material sets; molding compounds/die attach materials and 100% matte tin plate PLUS ANNEAL - e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations. Intersil Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.
Pinouts
ISL3232E (16 LD QFN) TOP VIEW
GND VCC C1+ V+
ISL4221E (16 LD QFN) TOP VIEW
FORCEOFF 14
C1C2+ C2V-
1 2 3 4 5 T2OUT 6 R2IN 7 R2OUT 8 T2IN
12 T1OUT 11 R1IN 10 R1OUT 9 T1IN V+ C1C2+ C21 2 3 4
16
15
VCC 13 12 GND 11 T1OUT 10 FORCEON 9 T1IN 8 INVALID
C1+ 5 V-
EN 6 R1IN
16
15
14
13
7 R1OUT
ISL4223E (20 LD QFN) TOP VIEW
FORCEOFF
20 V+ C1C2+ C2V1 2 3 4 5 6 T2OUT
19
18
17
GND 16 15 T1OUT 14 R1IN 13 R1OUT 12 FORCEON 11 T1IN 10 T2IN
7 R2IN
8 R2OUT
2
INVALID
VCC 9
C1+
EN
FN6045.3 February 13, 2008
ISL3232E, ISL4221E, ISL4223E Pin Descriptions
PIN VCC V+ VGND C1+ C1C2+ C2TIN TOUT RIN ROUT INVALID System power supply input (2.7V to 5.5V). Internally generated positive transmitter supply (+5.5V). Internally generated negative transmitter supply (-5.5V). Ground connection. External capacitor (voltage doubler) is connected to this lead. External capacitor (voltage doubler) is connected to this lead. External capacitor (voltage inverter) is connected to this lead. External capacitor (voltage inverter) is connected to this lead. TTL/CMOS compatible transmitter Inputs. 15kV ESD Protected, RS-232 level (nominally 5.5V) transmitter outputs. 15kV ESD Protected, RS-232 compatible receiver inputs. TTL/CMOS level receiver outputs. Active low output that indicates if no valid RS-232 levels are present on any receiver input. FUNCTION
FORCEOFF Active low to shut down transmitters and on-chip power supply. This overrides any automatic circuitry and FORCEON (see Table 2). FORCEON EN Active high input to override automatic power-down circuitry thereby keeping transmitters active. (FORCEOFF must be high). Active low receiver enable control.
Typical Operating Circuits
ISL3232E
+3.3V + + 0.1F 15 1 2 + 3 9 8 C1+ C1C2+ C2T1 T2 V14 VCC V+ 16 C +3 0.1F C4 0.1F + T1OUT T2OUT RS-232 LEVELS
C1 0.1F C2 0.1F
4 12 5
T1IN T2IN TTL/CMOS LOGIC LEVELS
R1OUT
10 R1 5k
11
R1IN
R2OUT
7 R2 5k
6
R2IN
GND 13
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FN6045.3 February 13, 2008
ISL3232E, ISL4221E, ISL4223E Typical Operating Circuits
ISL4221E
+3.3V + 0.1F 13 VCC V+ 1 + C3 0.1F C4
C1 0.1F C2 0.1F
16 + C1+ 2 C13 + C2+ 4 C29
V- 5 T1 11
+ 0.1F T1OUT R1IN RS-232 LEVELS
TTL/CMOS LOGIC LEVELS R1 OUT
T1IN
7 R1 15 EN FORCEOFF 10 FORCEON GND 12 INVALID 5k
6
14 8
VCC TO POWER CONTROL LOGIC
ISL4223E
+3.3V + + 0.1F 20 2 C1+ 17 VCC V+ 1 C +3 0.1F C4 0.1F + T1OUT T2OUT RS-232 LEVELS
C1 0.1F C2 0.1F
+
C13 C2+ 4 C2T1 T2
V-
5 15 6
T1IN T2IN TTL/CMOS LOGIC LEVELS
11 10
R1OUT
13 R1 5k
14
R1IN
R2OUT
8 19 EN R2 5k
7
R2IN
FORCEOFF 12 FORCEON GND 16 INVALID
18 9
VCC TO POWER CONTROL LOGIC
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FN6045.3 February 13, 2008
ISL3232E, ISL4221E, ISL4223E
Absolute Maximum Ratings
VCC to GND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V V+ to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 7V V- to GND. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.3V to -7V V+ to V- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14V Input Voltages TIN, FORCEOFF, FORCEON, EN . . . . . . . . . . . . . . . -0.3V to 6V RIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25V Output Voltages TOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2V ROUT, INVALID. . . . . . . . . . . . . . . . . . . . . . . . -0.3V to VCC +0.3V Short Circuit Duration TOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . See Specification Table
Thermal Information
Thermal Resistance (Typical)
JA (C/W) JC (C/W)
16 Ld QFN Package (Notes 1, 2). . . . . 35 4.3 20 Ld QFN Package (Notes 1, 2). . . . . 32 4.3 Maximum Junction Temperature (Plastic Package) . . . . . . +150C Maximum Storage Temperature Range . . . . . . . . . .-65C to +150C Pb-free reflow profile . . . . . . . . . . . . . . . . . . . . . . . . . .see link below http://www.intersil.com/pbfree/Pb-FreeReflow.asp
Operating Conditions
Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . .-40C to +85C
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product reliability and result in failures not covered by warranty.
NOTE: 1. JA is measured in free air with the component mounted on a high effective thermal conductivity test board with "direct attach" features. See Tech Brief TB379, and Tech Brief TB389. 2. For JC, the "case temp" location is the center of the exposed metal pad on the package underside.
Electrical Specifications
Test Conditions: VCC = 3V to 5.5V, C1 through C4 = 0.1F; Unless Otherwise Specified. Typicals are at TA = +25C TEST CONDITIONS TEMP (C) MIN (Note 4) TYP MAX (Note 4) UNITS
PARAMETER DC CHARACTERISTICS
Supply Current, Automatic Power-down All RIN Open, FORCEON = GND, FORCEOFF = VCC (Except ISL3232E) Supply Current, Power-down Supply Current, Automatic Power-down Disabled FORCEOFF = GND (Except ISL3232E) VCC = 3.15V All Outputs Unloaded, FORCEON = FORCEOFF = VCC
25 25 25
-
0.15 0.15 0.3
1 1 1.0
A A mA
LOGIC AND TRANSMITTER INPUTS AND RECEIVER OUTPUTS Input Logic Threshold Low Input Logic Threshold High TIN, FORCEON, FORCEOFF, EN TIN, FORCEON, FORCEOFF, EN VCC = 3.3V VCC = 5.0V Input Leakage Current Output Leakage Current Output Voltage Low Output Voltage High TIN, FORCEON, FORCEOFF, EN EN = VCC (Except ISL3232E) IOUT = 1.6mA IOUT = -1.0mA Full Full Full Full Full Full Full 2.0 2.4 0.01 0.05 0.8 1.0 10 0.4 V V V A A V V
VCC - 0.6 VCC - 0.1
AUTOMATIC POWER-DOWN (FORCEON = GND, FORCEOFF = VCC, Except ISL3232E) Receiver Input Thresholds to Enable Transmitters Receiver Input Thresholds to Disable Transmitters INVALID Output Voltage Low INVALID Output Voltage High Receiver Threshold to Transmitters Enabled Delay (tWU) Receiver Positive or Negative Threshold to INVALID High Delay (tINVH) Receiver Positive or Negative Threshold to INVALID Low Delay (tINVL) ISL4221E, ISL4223E Powers Up (See Figure 6) ISL4221E, ISL4223E Powers Down (See Figure 6) IOUT = 1.6mA IOUT = -1.0mA Full Full Full Full 25 25 25 -2.7 -0.3 VCC - 0.6 100 1 30 2.7 0.3 0.4 V V V V s s s
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FN6045.3 February 13, 2008
ISL3232E, ISL4221E, ISL4223E
Electrical Specifications
Test Conditions: VCC = 3V to 5.5V, C1 through C4 = 0.1F; Unless Otherwise Specified. Typicals are at TA = +25C (Continued) TEST CONDITIONS TEMP (C) MIN (Note 4) TYP MAX (Note 4) UNITS
PARAMETER RECEIVER INPUTS Input Voltage Range Input Threshold Low VCC = 3.3V VCC = 5.0V Input Threshold High VCC = 3.3V VCC = 5.0V Input Hysteresis Input Resistance TRANSMITTER OUTPUTS Output Voltage Swing Output Resistance Output Short-Circuit Current Output Leakage Current TIMING CHARACTERISTICS Maximum Data Rate Receiver Propagation Delay
25 25 25 25 25 25 25
-25 0.6 0.8 3
1.2 1.5 1.5 1.8 0.5 5
25 2.4 2.4 7
V V V V V V k
All Transmitter Outputs Loaded with 3k to Ground VCC = V+ = V- = 0V, Transmitter Output = 2V
Full Full Full
5.0 300 -
5.4 10M 35 -
60 25
V mA A
VOUT = 12V, VCC = 0V, or VCC = 3V to 5.5V, with Automatic Power-down or FORCEOFF = GND
Full
RL = 3k, CL = 1000pF, One Transmitter Switching Receiver Input to Receiver Output, CL = 150pF tPHL tPLH
Full 25 25 25 25 25 25
250 4 6
500 0.15 0.15 200 200 100 50 -
30 30
kbps s s ns ns ns ns V/s V/s
Receiver Output Enable Time Receiver Output Disable Time Transmitter Skew Receiver Skew Transition Region Slew Rate
Normal Operation (Except ISL3232E) Normal Operation (Except ISL3232E) tPHL - tPLH (Note 3) tPHL - tPLH VCC = 3.3V, RL = 3k to 7k, Measured From 3V to -3V or -3V to 3V CL = 150pF to 2500pF CL = 150pF to 1000pF
25 25
ESD PERFORMANCE RS-232 Pins (TOUT, RIN) Human Body Model IEC61000-4-2 Contact Discharge IEC61000-4-2 Air Gap Discharge All Other Pins NOTES: 3. Transmitter skew is measured at the transmitter zero crossing points. 4. Parts are 100% tested at +25C. Temperature limits established by characterization and are not production tested. Human Body Model 25 25 25 25 15 8 15 2 kV kV kV kV
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FN6045.3 February 13, 2008
ISL3232E, ISL4221E, ISL4223E Detailed Description
The ISL4221E, ISL4223E and ISL3232E operate from a single +2.7V to +5.5V supply, guarantee a 250kbps minimum data rate, require only four small external 0.1F capacitors, feature low power consumption, and meet all ElA RS-232C and V.28 specifications even with VCC = 3.0V. The circuit is divided into three sections: The charge pump, the transmitters and the receivers. input high whenever the UART powers down. Figure 3 also shows that the INVALID output can be used to determine when the UART should be powered down. When the RS-232 cable is disconnected, INVALID switches low indicating that the UART is no longer needed. Reconnecting the cable drives INVALID back high, indicating that the UART should be powered up.
VCC RXIN -25V VRIN +25V GND 5k RXOUT GND VROUT VCC
Charge-Pump
Intersil's new RS-232 devices utilize regulated on-chip dual charge pumps as voltage doublers, and voltage inverters to generate 5.5V transmitter supplies from a VCC supply as low as 3.0V. This allows them to maintain RS-232 compliant output levels over the 10% tolerance range of 3.3V powered systems. The efficient on-chip power supplies require only four small, external 0.1F capacitors for the voltage doubler and inverter functions. The charge pumps operate discontinuously (i.e., they turn off as soon as the V+ and V- supplies are pumped up to the nominal values), resulting in significant power savings.
FIGURE 1. INVERTING RECEIVER CONNECTIONS
VCC
VCC CURRENT FLOW VOUT = VCC
VCC
Transmitters
The transmitters are proprietary, low dropout, inverting drivers that translate TTL/CMOS inputs to EIA/TIA-232 output levels. Coupled with the on-chip 5.5V supplies, these transmitters deliver true RS-232 levels over a wide range of single supply system voltages. All ISL4221E, ISL4223E transmitter outputs disable and assume a high impedance state when the device enters the power-down mode (see Table 2). These outputs may be driven to 12V when disabled. The devices guarantee a 250kbps data rate for full load conditions (3k and 1000pF), VCC 3.0V, with one transmitter operating at full speed. Under more typical conditions of VCC 3.3V, RL = 3k, and CL = 250pF, one transmitter easily operates at 900kbps. Transmitter inputs float if left unconnected, and may cause ICC increases. Connect unused inputs to GND for the best performance.
Rx POWERED DOWN UART Tx GND
SHDN = GND
OLD RS-232 CHIP
FIGURE 2. POWER DRAIN THROUGH POWERED DOWN PERIPHERAL
VCC TRANSITION DETECTOR TO WAKE-UP LOGIC VCC RX POWERED DOWN UART ISL4221E, ISL4223E
INVALID VOUT = HI-Z ROUT TX TIN EN = VCC TOUT RIN
Receivers
All these RS-232 devices contain standard inverting receivers, and the ISL4221E, ISL4223E receivers three-state via the EN control line. All the receivers convert RS-232 signals to CMOS output levels and accept inputs up to 25V while presenting the required 3k to 7k input impedance (see Figure 1) even if the power is off (VCC = 0V). The receivers' Schmitt trigger input stage uses hysteresis to increase noise immunity and decrease errors due to slow input signal transitions. Receivers driving a powered down UART must be disabled to prevent current flow through, and possible damage to, the UART's protection diodes (see Figures 2 and 3). This can be accomplished on the ISL4221E, ISL4223E by driving the EN
FIGURE 3. DISABLED RECEIVERS PREVENT POWER DRAIN
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FN6045.3 February 13, 2008
ISL3232E, ISL4221E, ISL4223E
TABLE 2. POWER-DOWN AND ENABLE LOGIC TRUTH TABLE (EXCLUDING ISL3232E) RS-232 SIGNAL PRESENT AT RECEIVER INPUT? NO NO YES YES NO NO YES YES NO NO FORCEOFF FORCEON EN TRANSMITTER RECEIVER INVALID INPUT INPUT INPUT OUTPUTS OUTPUTS OUTPUT H H H H H H L L L L H H L L L L X X X X L H L H L H L H L H Active Active Active Active High-Z High-Z High-Z High-Z High-Z High-Z Active High-Z Active High-Z Active High-Z Active High-Z Active High-Z L L H H L L H H L L
MODE OF OPERATION Normal Operation (Auto Power-down Disabled) Normal Operation (Auto Power-down Enabled) Power-down Due to Auto Power-down Logic Manual Power-down Manual Power-down w/Rcvr. Disabled Manual Power-down Manual Power-down w/Rcvr. Disabled
Low Power Operation
These 3V devices require a nominal supply current of 0.3mA, even at VCC = 5.5V, during normal operation (not in power-down mode). This is considerably less than the 5mA to 11mA current required by comparable 5V RS-232 devices, allowing users to reduce system power simply by switching to this new family.
The time to recover from automatic power-down mode is typically 100s.
FORCEOFF PWR MGT LOGIC FORCEON INVALID ISL4221E, ISL4223E
Power-down Functionality (Excluding ISL3232E)
The already low current requirement drops significantly when the device enters power-down mode. In power-down, supply current drops to 150nA because the on-chip charge pump turns off (V+ collapses to VCC, V- collapses to GND) and the transmitter outputs three-state. Receiver outputs are unaffected by power-down; refer to Table 2 for details. This micro-power mode makes the ISL4221E, ISL4223E ideal for battery-powered and portable applications.
I/O UART CPU
Software Controlled (Manual) Power-down
The ISL4221E, ISL4223E family provides pins that allow the user to force the IC into the low power, standby state. The ISL4221E, ISL4223E utilize a two pin approach where the FORCEON and FORCEOFF inputs determine the IC's mode. For always enabled operation, FORCEON and FORCEOFF are both strapped high. To switch between active and power-down modes, under logic or software control, only the FORCEOFF input need be driven. The FORCEON state isn't critical, as FORCEOFF dominates over FORCEON. Nevertheless, if strictly manual control over power-down is desired, the user must strap FORCEON high to disable the automatic power-down circuitry. Connecting FORCEOFF and FORCEON together disables the automatic power-down feature, enabling them to function as a manual SHUTDOWN input (see Figure 4).
FIGURE 4. CONNECTIONS FOR MANUAL POWER-DOWN WHEN NO VALID RECEIVER SIGNALS ARE PRESENT
POWER MANAGEMENT UNIT
MASTER POWER-DOWN LINE 0.1F 1M
FORCEOFF
FORCEON
ISL4221E, ISL4223E
FIGURE 5. CIRCUIT TO PREVENT AUTO POWER-DOWN FOR 100ms AFTER FORCED POWER-UP
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FN6045.3 February 13, 2008
ISL3232E, ISL4221E, ISL4223E
VALID RS-232 LEVEL - ISL4221E, ISL4223E IS ACTIVE INDETERMINATE - POWER-DOWN MAY OR MAY NOT OCCUR 0.3V INVALID LEVEL - POWER-DOWN OCCURS AFTER 30s -0.3V INDETERMINATE - POWER-DOWN MAY OR MAY NOT OCCUR -2.7V VALID RS-232 LEVEL - ISL4221E, ISL4223E IS ACTIVE
2.7V
Some applications may need more time to wake up from shutdown. If automatic power-down is being utilized, the RS-232 device will re-enter power-down if valid receiver levels aren't reestablished within 30s of the ISL4221E, ISL4223E powering up. Figure 5 illustrates a circuit that keeps the ISL4221E, ISL4223E from initiating automatic power-down for 100ms after powering up. This gives the slow-to-wake peripheral circuit time to re-establish valid RS-232 output levels. The time to recover from automatic power-down mode is typically 100s.
INVALID Output (Excluding ISL3232E)
FIGURE 6. DEFINITION OF VALID RS-232 RECEIVER LEVELS
RECEIVER INPUTS TRANSMITTER OUTPUTS VCC 0 V+ VCC 0 V-
INVALID } REGION
INVALID OUTPUT
tINVL AUTOPWDN
tINVH PWR UP
The INVALID output always indicates whether or not a valid RS-232 signal (see Figure 6) is present at any of the receiver inputs (see Table 2), giving the user an easy way to determine when the interface block should power down. Invalid receiver levels occur whenever the driving peripheral's outputs are shut off (powered down) or when the RS-232 interface cable is disconnected. In the case of a disconnected interface cable where all the receiver inputs are floating (but pulled to GND by the internal receiver pull down resistors), the INVALID logic detects the invalid levels and drives the output low. The power management logic then uses this indicator to power-down the interface block. Reconnecting the cable restores valid levels at the receiver inputs, INVALID switches high, and the power management logic wakes up the interface block. INVALID can also be used to indicate the DTR or RING INDICATOR signal, as long as the other receiver inputs are floating, or driven to GND (as in the case of a powered down driver). INVALID switches low after invalid levels have persisted on all of the receiver inputs for more than 30s (see Figure 7). INVALID switches back high 1s after detecting a valid RS-232 level on a receiver input. INVALID operates in all modes (forced or automatic power-down, or forced on), so it is also useful for systems employing manual power-down circuitry. When automatic power-down is utilized, INVALID = 0 indicates that the ISL4221E, ISL4223E is in power-down mode.
FIGURE 7. AUTOMATIC POWER-DOWN AND INVALID TIMING DIAGRAMS
Automatic Power-down (Excluding ISL3232E)
Even greater power savings is available by using the automatic power-down function. When no valid RS-232 voltages (see Figure 6) are sensed on any receiver input for 30s, the charge pump and transmitters power-down, thereby reducing supply current to 150nA. Invalid receiver levels occur whenever the driving peripheral's outputs are shut off (powered down) or when the RS-232 interface cable is disconnected. The ISL4221E, ISL4223E powers back up whenever it detects a valid RS-232 voltage level on any receiver input. This automatic power-down feature provides additional system power savings without changes to the existing operating system. Automatic power-down operates when the FORCEON input is low, and the FORCEOFF input is high. Tying FORCEON high disables automatic power-down, but manual power-down is always available via the overriding FORCEOFF input. Table 2 summarizes the automatic power-down functionality.
Capacitor Selection
The charge pumps require 0.1F, or greater, capacitors for proper operation. Increasing the capacitor values (by a factor of 2) reduces ripple on the transmitter outputs and slightly reduces power consumption. When using minimum required capacitor values, make sure that capacitor values do not degrade excessively with temperature. If in doubt, use capacitors with a larger nominal value. The capacitor's equivalent series resistance (ESR) usually rises at low temperatures and it influences the amount of ripple on V+ and V-.
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FN6045.3 February 13, 2008
ISL3232E, ISL4221E, ISL4223E Power Supply Decoupling
In most circumstances a 0.1F bypass capacitor is adequate. In applications that are particularly sensitive to power supply noise, decouple VCC to ground with a capacitor of the same value as the charge-pump capacitor C1. Connect the bypass capacitor as close as possible to the IC.
VCC 0.1F +
C1
+
C1+
VCC
V+
+
C3
Transmitter Outputs when Exiting Power-down
Figure 8 shows the response of two transmitter outputs when exiting power-down mode. As they activate, the two transmitter outputs properly go to opposite RS-232 levels, with no glitching, ringing, nor undesirable transients. Each transmitter is loaded with 3k in parallel with 2500pF. Note that the transmitters enable only when the magnitude of the supplies exceed approximately 3V.
C2
+
C1ISL4221E, ISL4223E VC2+ C2TIN ROUT FORCEON 5k TOUT RIN +
C4
1000pF
VCC
FORCEOFF
Operation Down to 2.7V
ISL4221E, ISL4223E and ISL3232E transmitter outputs meet RS-562 levels (3.7V), at the full data rate, with VCC as low as 2.7V. RS-562 levels typically ensure inter operability with RS-232 devices.
FIGURE 9. TRANSMITTER LOOPBACK TEST CIRCUIT
5V/DIV T1IN
High Data Rates
The ISL4221E, ISL4223E and ISL3232E maintain the RS232 5V minimum transmitter output voltages even at high data rates. Figure 9 details a transmitter loopback test circuit, and Figure 10 illustrates the loopback test result at 120kbps. For this test, all transmitters were simultaneously driving RS-232 loads in parallel with 1000pF, at 120kbps. Figure 11 shows the loopback results for a single transmitter driving 1000pF and an RS-232 load at 250kbps. The static transmitters were also loaded with an RS-232 receiver.
T1OUT
R1OUT VCC = +3.3V C1 - C4 = 0.1F TIME (5s/DIV)
FIGURE 10. LOOPBACK TEST AT 120kbps
5V/DIV
FORCEOFF T1
5V/DIV T1IN
2V/DIV
T1OUT
T2 VCC = +3.3V C1 - C4 = 0.1F TIME (20s/DIV)
R1OUT VCC = +3.3V C1 - C4 = 0.1F TIME (2s/DIV)
FIGURE 8. TRANSMITTER OUTPUTS WHEN EXITING POWER-DOWN
FIGURE 11. LOOPBACK TEST AT 250kbps
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FN6045.3 February 13, 2008
ISL3232E, ISL4221E, ISL4223E Interconnection with 3V and 5V Logic
The ISL4221E, ISL4223E and ISL3232E directly interface with 5V CMOS and TTL logic families. Nevertheless, with the ISL4221E, ISL4223E and ISL3232E at 3.3V, and the logic supply at 5V, AC, HC, and CD4000 outputs can properly drive ISL4221E, ISL4223E and ISL3232E inputs, but ISL4221E, ISL4223E and ISL3232E outputs do not reach the minimum VIH for these logic families. See Table 3 for more information.
TABLE 3. LOGIC FAMILY COMPATIBILITY WITH VARIOUS SUPPLY VOLTAGES VCC SYSTEM POWER-SUPPLY SUPPLY VOLTAGE VOLTAGE (V) (V) 3.3 5 5 3.3 5 3.3
Human Body Model (HBM) Testing
As the name implies, this test method emulates the ESD event delivered to an IC during human handling. The tester delivers the charge through a 1.5k current limiting resistor, making the test less severe than the IEC61000 test which utilizes a 330 limiting resistor. The HBM method determines an ICs ability to withstand the ESD transients typically present during handling and manufacturing. Due to the random nature of these events, each pin is tested with respect to all other pins. The RS-232 pins on "E" family devices can withstand HBM ESD events to 15kV.
IEC61000-4-2 Testing
COMPATIBILITY Compatible with all CMOS families. Compatible with all TTL and CMOS logic families. Compatible with ACT and HCT CMOS, and with TTL. ISL4221E, ISL4223E and ISL3232E outputs are incompatible with AC, HC, and CD4000 CMOS inputs.
The IEC61000-4-2 test method applies to finished equipment, rather than to an individual IC. Therefore, the pins most likely to suffer an ESD event are those that are exposed to the outside world (the RS-232 pins in this case), and the IC is tested in its typical application configuration (power applied) rather than testing each pin-to-pin combination. The lower current limiting resistor coupled with the larger charge storage capacitor yields a test that is much more severe than the HBM test. The extra ESD protection built into this device's RS-232 pins allows the design of equipment meeting level 4 criteria without the need for additional board level protection on the RS-232 port. AIR-GAP DISCHARGE TEST METHOD For this test method, a charged probe tip moves toward the IC pin until the voltage arcs to it. The current waveform delivered to the IC pin depends on approach speed, humidity, temperature, etc., so it is difficult to obtain repeatable results. The "E" device RS-232 pins withstand 15kV air-gap discharges. CONTACT DISCHARGE TEST METHOD During the contact discharge test, the probe contacts the tested pin before the probe tip is energized, thereby eliminating the variables associated with the air-gap discharge. The result is a more repeatable and predictable test, but equipment limits prevent testing devices at voltages higher than 8kV. All "E" family devices survive 8kV contact discharges on the RS-232 pins.
15kV ESD Protection
All pins on ISL4221E, ISL4223E and ISL3232E devices include ESD protection structures, but the RS-232 pins (transmitter outputs and receiver inputs) incorporate advanced structures, which allow them to survive ESD events up to 15kV. The RS-232 pins are particularly vulnerable to ESD damage because they typically connect to an exposed port on the exterior of the finished product. Simply touching the port pins, or connecting a cable, can cause an ESD event that might destroy unprotected ICs. These new ESD structures protect the device whether or not it is powered-up, protect without allowing any latchup mechanism to activate, and don't interfere with RS-232 signals as large as 25V.
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ISL3232E, ISL4221E, ISL4223E Typical Performance Curves
6 TRANSMITTER OUTPUT VOLTAGE (V) 4 2 0 -2 -4 -6 VOUT 5 VOUT+ 20 1 TRANSMITTER AT 250kbps OTHER TRANSMITTERS AT 30kbps SLEW RATE (V/s)
VCC = 3.3V, TA = +25C
25
15 -SLEW +SLEW 10
0
1000
2000
3000
4000
5000
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
FIGURE 12. TRANSMITTER OUTPUT VOLTAGE vs LOAD CAPACITANCE
45 40 SUPPLY CURRENT (mA) 35 30 25 20 15 10 5 0 0 1000 2000 3000 4000 5000 20kbps 120kbps
FIGURE 13. SLEW RATE vs LOAD CAPACITANCE
ISL4221E SUPPLY CURRENT (mA)
45 40 250kbps 35 30 25 20 15 10 5 0 0 1000 2000 3000 4000 5000 20kbps 120kbps ISL4223E/ISL3232E 250kbps
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
FIGURE 14. SUPPLY CURRENT vs LOAD CAPACITANCE WHEN TRANSMITTING DATA
3.5 3.0 SUPPLY CURRENT (mA) 2.5 NO LOAD ALL OUTPUTS STATIC
FIGURE 15. SUPPLY CURRENT vs LOAD CAPACITANCE WHEN TRANSMITTING DATA
Die Characteristics
SUBSTRATE POTENTIAL (POWERED UP): GND TRANSISTOR COUNT:
2.0 1.5 1.0 0.5 0 2.5
ISL3232E: 296 ISL4221E: 286 ISL4223E: 357 PROCESS: Si Gate CMOS
3.0 3.5 4.0 4.5 5.0 5.5 6.0
SUPPLY VOLTAGE (V)
FIGURE 16. SUPPLY CURRENT vs SUPPLY VOLTAGE
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FN6045.3 February 13, 2008
ISL3232E, ISL4221E, ISL4223E Quad Flat No-Lead Plastic Package (QFN) Micro Lead Frame Plastic Package (MLFP)
L16.5x5B
16 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE (COMPLIANT TO JEDEC MO-220VHHB ISSUE C) MILLIMETERS SYMBOL A A1 A2 A3 b D D1 D2 E E1 E2 e k L L1 N Nd Ne P 0.25 0.35 2.95 2.95 0.28 MIN 0.80 NOMINAL 0.90 0.20 REF 0.33 5.00 BSC 4.75 BSC 3.10 5.00 BSC 4.75 BSC 3.10 0.80 BSC 0.60 16 4 4 0.60 12 0.75 0.15 3.25 3.25 0.40 MAX 1.00 0.05 1.00 NOTES 9 9 5, 8 9 7, 8 9 7, 8 8 10 2 3 3 9 9 Rev. 1 10/02 NOTES: 1. Dimensioning and tolerancing conform to ASME Y14.5-1994. 2. N is the number of terminals. 3. Nd and Ne refer to the number of terminals on each D and E. 4. All dimensions are in millimeters. Angles are in degrees. 5. Dimension b applies to the metallized terminal and is measured between 0.15mm and 0.30mm from the terminal tip. 6. The configuration of the pin #1 identifier is optional, but must be located within the zone indicated. The pin #1 identifier may be either a mold or mark feature. 7. Dimensions D2 and E2 are for the exposed pads which provide improved electrical and thermal performance. 8. Nominal dimensions are provided to assist with PCB Land Pattern Design efforts, see Intersil Technical Brief TB389. 9. Features and dimensions A2, A3, D1, E1, P & are present when Anvil singulation method is used and not present for saw singulation. 10. Depending on the method of lead termination at the edge of the package, a maximum 0.15mm pull back (L1) maybe present. L minus L1 to be equal to or greater than 0.3mm.
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FN6045.3 February 13, 2008
ISL3232E, ISL4221E, ISL4223E Quad Flat No-Lead Plastic Package (QFN) Micro Lead Frame Plastic Package (MLFP)
L20.5x5
20 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE MILLIMETERS SYMBOL A A1 A2 A3 b D D1 D2 E E1 E2 e k L N Nd Ne P 0.20 0.35 2.95 2.95 0.23 MIN 0.80 NOMINAL 0.90 0.02 0.65 0.20 REF 0.30 5.00 BSC 4.75 BSC 3.10 5.00 BSC 4.75 BSC 3.10 0.65 BSC 0.60 20 5 5 0.60 12 0.75 3.25 3.25 0.38 MAX 1.00 0.05 1.00 NOTES 9 9 5, 8 9 7, 8 9 7, 8 8 2 3 3 9 9 Rev. 4 11/04 NOTES: 1. Dimensioning and tolerancing conform to ASME Y14.5-1994. 2. N is the number of terminals. 3. Nd and Ne refer to the number of terminals on each D and E. 4. All dimensions are in millimeters. Angles are in degrees. 5. Dimension b applies to the metallized terminal and is measured between 0.15mm and 0.30mm from the terminal tip. 6. The configuration of the pin #1 identifier is optional, but must be located within the zone indicated. The pin #1 identifier may be either a mold or mark feature. 7. Dimensions D2 and E2 are for the exposed pads which provide improved electrical and thermal performance. 8. Nominal dimensions are provided to assist with PCB Land Pattern Design efforts, see Intersil Technical Brief TB389. 9. Features and dimensions A2, A3, D1, E1, P & are present when Anvil singulation method is used and not present for saw singulation. 10. Compliant to JEDEC MO-220VHHC Issue I except for the "b" dimension.
All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems. Intersil Corporation's quality certifications can be viewed at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com 14
FN6045.3 February 13, 2008

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